Dr. Saqib Khan


A suspension is a biphasic dose form consisting of a coarse dispersion of insoluble solid particles in a liquid media. Particles with sizes typically bigger than 0.1 m in diameter (disperse phase) are dispersed in a powdery state in another phase (continuous phase).

Advantages of Suspension

Allows for greater chemical stability in several medications. Penicillin G Procaine, for instance, has An increased rate of bioavailability shown when a drug is administered in a solution rather than another form. The following is a list of bioavailability in order of decreasing effectiveness:

  • Solution > suspension > capsule > compressed tablet > coated tablet
  • Time and effect onset may be modulated. Protamine zinc insulin suspension, for instance
  • Masking tastes, such as chloramphenicol palmitate


  • Without unit dosage packaging, it is impossible to ensure that each dose of suspension is uniform and correct.
  • Deficiencies in stability, sedimentation, and caking might be an issue.
  • Because of its large size, special care must be used while moving it.
  • It is also very hard to formulate

Ideal Suspension

A perfect ideal suspension would have the following:

  • Aesthetic appeal, therapeutic efficacy, and chemical and physical stability
  • Shaking ought to result in a homogeneous consistency
  • It should take time to settle, but it should be easy to disperse with a little shake of the container
  • A thick cake should not develop


1.      Flocculated Suspension

Particles in the dispersed phase agglomerate, forming a network-like structure in the surrounding media. There is no solid cake-like aggregate formed. These clumps disperse quickly because of the fast rate of sedimentation and the granular nature of the sediment that is generated.


  • There is a lot of space between the grains of silt. The particles are not strongly attached to each other.
  • The sediment may be evenly distributed with only a little shaking.
  • It has plastic or pseudoplastic characteristics.
  • In this suspension, pressure is distributed equally everywhere.
  • The viscosity of this solution is essentially constant regardless of the depth.
  • Flocculated suspension accomplishes the desired goal of dosage homogeneity.

2.   Deflocculated system

The solid particles in this system are autonomous entities floating freely in a dispersion liquid. Hard cake is made of sediments. The sluggish rate of sedimentation allows the solid medication particles to gently settle. Redistribution becomes more challenging as sediments accumulate.


  • Smaller particles with a slow settling rate.
  • The sediment, over a period of time, gets extremely densely packed and makes a non-dispersible cake.
  • Although the bulk of particles has settled out, the supernatant liquid is still murky.
  • The line separating sediment from supernatant is not sharp.

Suspension formulation

  • Active Pharmaceutical Ingredient (Drug)
  • Vehicle/mobile phase (suspending medium)
  • The wetting agents
  • Substances (Suspending, Flocculating agent) that let you regulate sedimentation and stability
  • Acid-base buffers
  • Other Ingredients (color, flavor, taste preservatives)

Method of Preparation

Step- 1- Active Ingredient wetting and dispersal. Dry milling is used to get a certain particle size. Mixing and homogenization are optimized when applied to a low-viscosity section of the product. To make it more wet, you may add a wetting agent.

Step-2- The dispersed solid is stabilized by adding electrolytes, which generate charges around individual particles and facilitate electrical repulsion, thereby preventing them from coming into contact with one another.

Step-3- In order to fully hydrate the polymer, the vehicle-polymer combination must be prepared and let to remain for at least 24 hours.

Step -4- The active component is introduced to the vehicle and mixed at a low speed to create a dispersion. After that, we homogenize the mixture to make sure everything is evenly distributed.

Step-5- Put in the last of the ingredients and give it a good stir.

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When compared to other dosage forms, what advantages does a Suspension Dosage Form have?

The ability of suspension dosage forms to deliver medicine locally makes them ideal for the treatment of localized illnesses. Suspension dosage forms are convenient since they may be administered locally or consumed orally. They may be adjusted to meet the demands of individual therapies since various compounds can sometimes be suspended inside the liquid.

Q: Do suspension have any side effects?

Suspension Dosage Forms may have negative effects, but that is true of any drug. Typical adverse reactions include of diarrhea, vomiting, and stomach discomfort. Because the particles in the solution might set off an immunological response, there may also be an elevated risk of allergic responses. You should always check with your doctor before taking a suspension.

By Dr. Saqib Khan

I am a medical professional and research scholar having vast experience in Computer-aided drug discovery and organic Synthetic Chemistry. I also have a passion for academic and medical writing.

2 thoughts on “Suspension – Its Types and Methods of Preparation”
  1. Is it possible to convert iv drug into oral suspension dosage form? how it will effect the solubility of the drug?

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